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Poliovirus infection - including symptoms, treatment and prevention

Poliomyelitis or polio is an infection caused by the polio virus. It is a serious disease affecting a person’s brain and spinal cord. Infection with the poliovirus can lead to a life-threatening muscular paralysis of the body.

In the last 20 years the number of polio cases around the world has reduced. This is largely due to global vaccination programs that aim to immunise people against the poliovirus.

Countries such as North and South America, the western Pacific region (including Australia) and Europe are now all polio-free; however cases are still being reported in some parts of Asia and Africa.

Poliovirus infection is a notifiable condition1

How polio is spread

People can become infected with polio when they ingest the poliovirus though their mouth. Ingestion can occur in the following ways:

eating food prepared by someone who has polio

drinking untreated water that has been contaminated with the poliovirus via sewage

contact with the nose and throat discharge of a person infected with the poliovirus for example contact with soiled handkerchiefs or discarded tissues

contact with objects or surfaces touched by an infected person whose hands contain traces of faeces or alternatively having direct contact with the infected persons hands

inhaling or ingesting airborne droplets from the coughs and sneezes of someone infected with poliovirus.

Polio can be easily transmitted when someone infected with the poliovirus has close contact with many other people, such as in day care centres and family homes.

Signs and symptoms

Most people infected with the poliovirus will have no symptoms. Ten per cent of infected people may experience flu-like symptoms such as:

fever

fatigue

nausea

vomiting

headache

occasionally neck and back stiffness – referred to as non-paralytic aseptic meningitis (inflammation of the lining of the brain and spinal cord).

Less than 1% of people infected with poliovirus develop severe muscle weakness (acute flaccid paralysis) affecting the limbs, diaphragm muscle (essential for breathing), and the head and neck muscles.

The risk of permanent limb paralysis is less than 1%. Death occurs in 2 to 5% of children and 15 to 30% of adults with paralytic polio.

Diagnosis

Cases are diagnosed on signs and symptoms; and also by a laboratory test for the poliovirus on a person’s throat secretions, faeces or CSF (cerebrospinal fluid: the fluid surrounding the brain and spinal cord).

Incubation period

(time between becoming infected and developing symptoms)

Typically 7 to 14 days with a range of 3 to 35 days.

Infectious period

(time during which an infected person can infect others)

Transmission is possible as long as the poliovirus is shed.

The poliovirus can stay in the throat for about 7 days and in the faeces for 3 to 6 weeks.

Treatment

There is no cure for poliovirus infection.

Treatment focuses on managing the consequences of severe muscle weakness. This may include admission to intensive care to assist with breathing, and physiotherapy or medicines to reduce muscle spasm.